Screening and identification of thermophilic cellulolytic bacteria isolated from sawdust compost

D T H Phuong,D T Tuyen,L V Thang

doi:10.35885/1684-7318-2021-3-348-357

D T H Phuong, D T Tuyen + Show 1 more

Open Access

https://doi.org/10.35885/1684-7318-2021-3-348-357

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Abstract

Composting process mainly depends on the metabolic pathways of the microorganism and involves the activity of different enzymes. Thermophilic cellulase-producing bacteria isolated from sawdust compost were tested for formation of a visible zone around the colonies on the agar plates medium containing carboxymethyl cellulose at 50ºC. Screening of carboxymethyl cellulase producing isolates was further realized on the basis in liquid medium by DNS method. Among 29 isolates investigated, V1 and V11 strains exhibited maximum enzyme activity of 1.9 and 2.3 U/mL, respectively. These isolates were selected for morphological, physiological and biochemical studies and 16S rRNA gene analysis. They were found a Gram-positive, rod-shaped spore forming cells, which were identified as Bacillus megaterium (V1) and Bacillus subtilis (V11) based on cell morphology, nucleotide homology and phylogenetic analysis. The optimal temperature for activity of endoglucanases (CMCase) ranged from 35–45°C (strain V1) and 40– 50ºC (strain V11). Our findings showed that Bacillus megaterium (V1) and Bacillus subtilis (V11) cellulase demonstrate thermophilic characteristics within wide range of temperature and meets the requirements for commercial enzymes.

Highlights

Composting is the process of biological decomposition of the organic substrates and considered as a promising source of new thermophilic bacteria and thermostable enzymes (Alfreider et al, 2002)
The various of thermophilic bacterial strains of garden (76.1%) with two strains identified as B. thermodenitrificansi and B. licheniformis indicated by Bhattacharya and Pletschke (2014)
Some thermophilic cellulase-producing bacteria strains from industrial waste compost were found and identified as B. amyloliquefaciens B13C, B. licheniformis 1, B. subtilis subsp. spizizenii 6, B. subtilis subsp. subtilis B7B (Amore et al, 2013 a, b)

Summary

Introduction

Composting is the process of biological decomposition of the organic substrates and considered as a promising source of new thermophilic bacteria and thermostable enzymes (Alfreider et al, 2002). For all kind of compost, the most recognized group being able to grow well at temperature ranged from at 30 to 50°C are various members of the genus Bacillus belonging to thermophilic Bacilli (Bhattacharya, Pletschke, 2014). A number of thermophilic cellulolytic bacteria isolated from diverse sources of compost were reported. Maheshwari (2014) indicated a greater number of species of Bacillus from thermophilic compost samples containing manure, corn and sawdust. Some thermophilic cellulase-producing bacteria strains from industrial waste compost were found and identified as B. amyloliquefaciens B13C, B. licheniformis 1, B. subtilis subsp. Some thermophilic cellulase-producing bacteria strains from industrial waste compost were found and identified as B. amyloliquefaciens B13C, B. licheniformis 1, B. subtilis subsp. spizizenii 6, B. subtilis subsp. subtilis B7B (Amore et al, 2013 a, b)

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